Just curious as to why you say NOT to use the ailerons ?

At a "slow" glide speed either will/could bring you undone if used too much. Rudder only more likely to cause a stall and spin situation at low speed. Rudder yaws the plane, speeding one wing up relative to the other, therefore creating extra lift on the faster wing therefore roll into a turn, BUT requires opposite rudder to correct or straighten the turn on all but high dihedral or polyhedral wings which puts the plane out of balance again but whilst in a banked turn this time. Remember also that at lower speeds the controls are less effective so rudder would need to be applied for a longer period to produce the desired effect = more time spent out of balance and in a side slip which produces more drag therefore slowing the plane, therefore requiring the nose to be lowered to keep flying speed, therefore reducing the glide distance available.
Aileron increases angle of attack on the down going side and decreases AOA on the up going side, therefore a roll and turn, again, the opposite inputs are req'd to level the wings and stop the turn. Small inputs of aileron will produce almost nill yawing motion and very little difference in stalling speeds over the wings. Due to the almost nill yawing motion the plane stays in balance therefore not increasing drag as in a rudder only turn.
ANY turn in a glide situation will require more altitude to be given up than gliding straight with wings level, so keep all turns in a deadstick situation to a minimum. NEVER turn away from the landing zone unless you have a lot of altitude to play with. S turns will loose alt quickly if needed whilst keeping the landing zone in front of the plane.
NEVER in my days of full scale flying instructing did we teach a student to use rudder only in a glide approach, small aileron inputs was the method to produce a balanced minimum height loss turn in a glide.